Most of us tend to order a pizza based on the amount we plan to eat—and there's nothing wrong with that—but if you're trying to make your dollar stretch as far as it can, your best bet is to just order the biggest one you can buy. Why? The increase in size to cost always comes out in your favor. Here's why.

One day last year, an engineer and I went to a pizza place for lunch. The engineer told me he wasn't very hungry, but he said he was going to get the 12-inch medium instead of the 8-inch small — because the medium was more than twice as big as the small, and it cost only a little bit more. This sort of blew my mind.

...The math of why bigger pizzas are such a good deal is simple: A pizza is a circle, and the area of a circle increases with the square of the radius.

So, for example, a 16-inch pizza is actually four times as big as an 8-inch pizza.

And when you look at thousands of pizza prices from around the U.S., you see that you almost always get a much, much better deal when you buy a bigger pizza.

They also include an interactive graph that compares average pizza prices from pizzerias and chains across the country. You can drag the slider at the bottom of their graph to see exactly how much larger that bigger pizza is compared to the smaller ones, and at the average prices for each, how much you actually come out ahead. For example, One 18-inch pizza has roughly the same area as 1.7 14-inch pizzas or 5.1 8-inch pizza, To get the same amount of pizza you get in an $18.68 18-inch pizza, you'd have to spend an extra $5.29 on 14-inch pizzas, or an extra $23.09 on 8-inch pizzas. See how the numbers add up? It's almost universally a better deal—mathematically, mind you—to just get the bigger pizza.

Of course, this is a mathematical exercise—a rational, logical method of determining how to get the most return on your pizza investment. Obviously it doesn't make sense to buy a massive pizza if you can't eat it all, don't want to overeat, or have no way to store the leftovers. Hit the link below to see the original piece, and to play with the Pizza Calculator and see the math for yourself.